1. Field of the Invention
The invention relates generally to a piezoelectric drive arrangement, and more particularly, to a piezoelectric drive arrangement usable in automatic focusing systems or general deflection and deviation systems.
2. Description of the Prior Art
Known from German Offenlegungsschrift No. 25 24 854 is a piezoelectric drive arrangement for a mosaic print head, which consists of two flat, elongated piezoelectric transducers which are undetachably connected to each other and which are arranged in layers one on top of the other. Both transducers have a common control electrode to which a control potential is applied. The respective counterelectrodes are connected to a constant potential.
Known from German Offenlegungsschrift No. 25 24 893 is, furthermore, a mosaic print head with piezoelectric drive elements which, after the electrodes have been subjected to an electric field changing in steps, move away from a large stationary mass, causing an image to be printed on the record carrier as a result of their mass moment of inertia.
In German Offenlegungsschrift No. 24 26 331 a piezoelectric light beam deflector is described which has a mirror pivotable about an axis. This axis is supported between the ends of two piezoelectric disks. In the case of an oppositely directed length change of the two disks, resulting from the application of electric voltages, the axis moves along the surfaces of the disk.
In German Offenlegungsschrift No. 27 10 935 a matrix printer with piezoelectrically driven print needles is described. This printer is provided with a buckling spring deflectable in response to an electrically controlled expansion of a piezocrystal arrangement. This piezocrystal arrangement consists of piezocrystal elements which are arranged one behind the other in the direction of polarization and which have two pole faces each. The piezocrystal elements are arranged in such a manner that the pole faces of the same polarization polarity are aligned to each other. All pole faces with a positive polarization polarity are connected to the negative pole of a control voltage source, whereas the other pole faces with a negative polarization polarity are connected to the positive pole of this control voltage source. Thus, the same control voltage is applied to each piezocrystal element. The partial expansions of the individual piezocrystal elements add up to a desired stroke when the piezocrystal elements are correspondingly controlled by means of control pulses.
Also known are a plurality of focusing systems, wherein optical means have to be readjusted for focusing, for example, a light beam at a particular point. Such arrangements are known, for example, from German Offenlegungsschriften Nos. 27 53 436, 20 12 995, and 26 56 730.
In addition, in the publication "Disk" (Tentative B-900 ) by Robert Bosch GmbH, Geschaftsbereich Fernsehanlagen, Darmstadt/Deutschland, a "Professional Optical Video Disk System" is described, whereby for the production of video image disks, information is written onto the video disk by means of a laser beam. As slight falsifications of the video image have no detrimental effect, no extremely high resolutions are required for the focusing system for focusing the laser beam. Therefore, the focusing arrangement can be realized by means of light, and thus cheaper, lenses (no quality lenses) and by means of a moving coil drive suitable for such light lenses.